Black★Matagi is a girl with short black hair and purple eyes. A purple-colored flame shoots from her left eye and her right is covered by a black eyepatch. She wears an outfit similar to a sailor uniform, with a white collar, long sleeves, a short pleated skirt and a predominant black color scheme. She appears to wear a blouse with thin shoulder straps under her outfit. Black★Matagi also wears a pair of knee-high boots. Her accessories are a pair of headphones and a white armband with a black pentagram design.

Her weapon is a gunblade, a large artillery weapon with an even larger blade attached to its end. Its overall length can rival Black★Matagi's height.